1. Field of the Invention
The present invention relates to a liquid-container module, a liquid container, a recording apparatus, and a control method, and more particularly, to a liquid container including a light-emitting unit, such as a light-emitting diode (LED), for optically presenting various information.
2. Description of the Related Art
Recently, as digital cameras have come into widespread use, a recording method called non-PC recording has become popular in which a digital camera is directly connected to a printer that serves as a recording apparatus to perform a recording operation without using a personal computer (PC). In addition, another recording method in which a card-shaped information storing medium for a digital camera is directly attached to a printer for data transmission to perform a printing/recording operation has also become popular.
A method for checking an amount of ink remaining in an ink tank of a printer is discussed in, for example, Japanese Patent Laid-Open No. 7-76104. According to this method, data regarding the amount of remaining ink is stored in a storage element, such as a memory, provided on the ink tank. The printer accesses the storage element to obtain the data regarding the amount of remaining ink and displays the data on a monitor via a PC.
However, also in non-PC recording, there is a demand to check the amount of ink remaining in the ink tank without using a PC. If a user recognizes that there is only a small amount of ink remaining in the ink tank, the user can replace the ink tank with a new ink tank before starting the printing/recording operation, so that failure due to ink shortage can be prevented.
A typical structure for informing the user of the state of the ink tank includes a display element, such as an LED. Japanese Patent Laid-Open No. 4-275156 discloses a structure including two LEDs on an ink tank that is integrated with a recording head. The two LEDs are turned on in two steps in accordance with the amount of remaining ink.
Similarly, Japanese Patent Laid-Open No. 2002-301829 discusses a structure in which a lamp that is turned on in accordance with the amount of remaining ink is provided on an ink tank. This publication also discusses a recording apparatus including four ink tanks, each of which is provided with a lamp discussed in Japanese Patent Laid-Open No. 4-275156.
Japanese Patent Laid-Open No. 7-76104 discusses a timing chart showing timing at which a storage element (ROM) provided on an ink tank is accessed. However, the ink tank is not provided with a light-emitting unit, such as an LED. The other publications discuss structures in which an LED and a storage element, such as electrically erasable programmable read-only memory (EEPROM), are mounted on an ink tank or a cartridge. However, a control method including timing at which the LED is turned on and off is not discussed.
In general, to turn on an LED, a driver for driving the LED performs an operation (ON operation) for applying a power source voltage to the LED while an input signal is ON. To turn off the LED, the driver performs an operation (OFF operation) for switching off the power source voltage applied to the LED. Accordingly, when the ON/OFF operation in which the power source voltage is applied or switched off is performed to turn on or off the LED, a current higher than that applied for driving a control circuit or a memory provided on a semiconductor substrate is applied to a circuit of the LED. Therefore, there is a risk that noise will be generated when the relatively high rush current is applied.
The LED and the EEPROM mounted on the ink tank are controlled via a signal line connecting an electrical contact on the ink tank and an electrical contact on a cartridge in which the ink tank is mounted. For example, the printer transmits an identifier corresponding to the color of ink contained in the ink tank and a signal for controlling the illumination of the LED to the EEPROM mounted on the ink tank, so that the illumination of the LED provided on the ink tank corresponding to the identifier can be controlled.
However, if the noise generated due to the relatively high current applied to the circuit of the LED is input to the signal line for signal transmission, transmission and reception of the identifier and the control signal are disturbed. Accordingly, there is a risk that accurate signals cannot be transmitted to the ink tank. When accurate signals cannot be transmitted, the operation of turning on and off the LED and the operation of writing to and reading from the EEPROM cannot be performed normally. As a result, accurate information and recording result cannot be provided to the user.